• Fire Science and Engineering
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• v.15 no.4
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• pp.1-9
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• 2001

The purpose of this study is to set up disaster prevention plan and risk assessment system considering combustion velocity at traditional housing zone. The combustion velocity analysis could contribute to build in disaster prevention technique through the potential risk analysis of the area, such analysis also able to set up comprehensive disaster prevention management system. Following results have achieved through the combustion velocity calculation. \circled1 The combustion velocity was calculated in order of the below winds, the above winds and the side winds. \circled2 It must be careful to set up disaster prevention plan in case of the below winds. \circled3 The combustion velocity was calculated at the density Bone where neighboring Distance and Length was small. \circled4 It proved that factors of each parameter not mostly effect to analyse the combustion velocity in limit of the 30 minutes after ignition. \circled5 At the density zone where Distance and Length is small the duration of transfer to neighboring house takes up to 4 minutes, it is required to set up of emergency response plan to minimize the fire dispersion.

• Journal of the Korean Society of Combustion
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• v.10 no.1
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• pp.1-6
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• 2005

This paper presents the combustion characteristics of hydrocarbon fuel from a conventional pressure-swirl nozzle of a small-scale burner. The nozzle has orifice diameters of 0.256 mm and liquid flow rates ranging from 50 to 64 mL/min were selected for the experiments. The furnace temperature distribution along the axial distance, the gas emission such as CO, $CO_2$, NOx, $SO_2$, flue gas temperature, and combustion efficiency were studied. The local furnace and flue gas temperatures decreased with an increase in air velocity. At injection pressures of 1.1 and 1.3 MPa the maximum furnace temperatures occurred closer to the burner exit, at an axial distance of 242 mm from the diffuser tip. The CO and $CO_2$concentrations decreased with an increase in air velocity, but they increased with an increase in injection pressure. The effect of air velocity on NOx was not clearly seen at low injection pressures, but at injection pressure of 1.3 MPa it decreased with an increase in air velocity. The effect of air velocity on $SO_2$ concentration level is not well understood. The combustion efficiency decreased with an increase in air velocity but it increased with an increase in injection pressure. It is recommended that injection pressure less than 0.9 MPa with air velocity not above 8.0 m/s would be suitable for this burner.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.48-57
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• 2003

A cylindrical constant volume combustion chamber was used to investigate the flow characteristics at spark plug and the combustion characteristics of homogeneous charge methane-air mixture under various initial pressure, excess air ratio and ignition times in quiescent mixture. The flow characteristics such as mean velocity and turbulence intensity was analyzed by hot wire anemometer. Combustion pressure development measured by piezoelectric pressure transducer and flame propagation acquired by ICCD camera were used to investigate the effect of initial pressure, excess air ratio and ignition times on pressure, combustion duration, flame speed and burning velocity. Mean velocity and turbulence intensity had the maximum value at 200 or 300ms and then decreased to near 0 value gradually after 3 seconds. Combustion duration, flame speed and burning velocity were observed to be promoted with excess air ratio of 1.1, lower initial pressure and ignition time of 300ms.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.2
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• pp.75-83
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• 2001

This paper presents the evaluation of combustion characteristics of sing-hole plasma jet ignitions in comparison with conventional spark ignition for variable of swirl velocity. Plasma jet plugs are three types according to ejecting directions : center of chamber, positive and negative swirl flow direction. Experiments are carried out for equivalent ratio 1.0 of LPG-air mixture in a constant volume cylindrical vessel. Not only the flame propagation is photographed at intervals, but the pressure variation in the combustion chamber is also recorded throughout the entire combustion process. The results show that the plasma jet ignitions and spark ignition enhance the overall combustion rate by increasing the swirl velocity. The dependence of the combustion rate swirl velocity leade to the conclusion that the placma jet plug, which ejects plasma jet to the cwnter of combustion chamber is the most desirable ignitor than other plugs.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.8
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• pp.1089-1096
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• 2003

An experiment was performed to investigate lift-off, blow-off and combustion characteristics of a lifted coaxial diffusion flame according to fuel jet and air velocity. A jet diffusion flame which is attached on the nozzle rim begins to be lifted with increase of air velocity, and finally becomes blow-off at higher air velocity. In experiment, blow-off limit increased with increase of fuel jet velocity, however lift-off occurred at lower air velocity. Flame structure and combustion characteristics were examined by schlieren photos, temperature distributions and emission concentration distributions. Flame temperature became higher at midstream and its RMS became larger at up and downstream with increase of air velocity. Local NO concentration decreased but $CO_2$concentration increased with increase of air velocity, which shows combustion reaction becomes close to be stoichiometric at higher air velocity in spite of lift-off.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.8
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• pp.853-862
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• 2006

The present study is numerically investigated the flame structure of non-premixed counterflow jet flames using the laminar flamelet model Detailed flame structures with the fuel composition of 40% CO, 30% $H_2$. 30% $N_2$ and an oxidizer composition of 79% $N_2$ and 21% $O_2$ in a non-premixed counterflow flame are studied numerically. This study is aimed to investigate the effects of axial velocity gradient and combustion atmosphere pressure on flame structure. The results show that the role of axial velocity gradient on combustion processes is globally opposite to that of combustion atmosphere pressure. That is, chemical nonequilibrium effects become dominant with increasing axial velocity gradient, but are suppressed with increasing ambient pressure. Also, the flame strength is globally weakened by the increase of axial velocity gradient but is augmented by the increase of ambient pressure. However, flame extinction is described better on the basis of only chemical reaction and in this study axial velocity gradient and ambient pressure play a similar role conceptually such that the increase of axial velocity gradient and ambient pressure cause flame not to be extinguished and extend the extinction limit, respectively. Consequently it is suggested that a combustion process like flame extinction is mainly influenced by the competition between the radical formation reaction and the third-body recombination reaction.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• v.10 no.1
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• pp.76-82
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• 2005

This paper presents the combustion characteristics of hydrocarbon fuel from a conventional pressureswirl nozzle of a small-scale burner. The nozzle has orifice diameters of 0.256 mm and liquid flow rates raging from 50 to 64 mL/min were selected for the experiments. The furnace temperature distribution along the axial distance, the gas emission such as CO, $CO_2,\;NOx,\;S0_2,$ flue gas temperature, and combustion efficiency were studied. The local furnace and flue gas temperatures decreased with an increase in air velocity. At injection pressures of 1.1 and 1.3 MPa the maximum furnace temperatures occurred closer to the burner exit, at an axial distance of 242 mm from the diffuser tip. The CO and $CO_2$ concentrations decreased with an increase in air velocity, but they increased with an increase in injection pressure. The effect of air velocity on NOx was not clearly seen at low injection pressures, but at injection pressure of 1.3 MPa it decreased with an increase in air velocity. The effect of air velocity $SO_2$ concentration level is not well understood. The combustion efficiency decreased with an increase in air velocity but it increased with an increase in injection pressure. It is recommended that injection pressure less than 0.9 MPa with air velocity not above 8.0 m/s would be suitable for this burner.

• Journal of the Korean Society of Combustion
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• v.22 no.3
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• pp.8-16
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• 2017

MILD combustion was first developed to suppress thermal NOx formation in combustor for heating industrial furnaces. In this paper, the effect of co-flow MILD combustor geometry and operating conditions on the formation of MILD combustion was analyzed using 3 dimensional numerical simulation. The numerical simulations were carried out using ANSYS Fluent. The combustion and turbulence flow was modeled using the Eddy Dissipation Concept(EDC) model and realizable $k-{\varepsilon}$ model respectively. The results show that the high temperature region and average temperature decreased due to an increase in the air velocity and decrease the wall thickness of fuel nozzle. In particular, the MILD combustion flame was found to be stable with a combustion flame region at fuel velocity 10 m/s, air velocity 20 m/s, fuel nozzle thickness 1.0 mm, equivalence ratio 0.9, and outlet area ratio 40%.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.1
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• pp.99-108
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• 2004

Fundamental combustion characteristics, such as the combustion potential, burning velocity and flame stability, for the practical utilization of LFG(Landfill gas) and LFG-blended fuels were experimentally investigated. The combustion potentials(CP) of LFG-blended fuels calculated from the previously suggested formulae were compared with burning velocities obtained by present experiments. The results showed that the previous formulae fur CP of LFG-blended fuels were not agreed with the experimental burning velocity, and these formulae should be revised. To provide an useful information needed to design the combustion devices, a triangular diagram was suggested for the maximum burning velocity of the mixture of CH$_4$, LPG and LFG. From the investigation of the burning velocity and the flame stability in a practical combustor, it was noted that the LFG-blended fuels, of which heating values or Wobbe indices were adjusted to that of natural gas, could be used as an alternative fuel of natural gas.

• Journal of the Korean Society of Safety
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• v.11 no.1
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• pp.75-83
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• 1996

This paper was concerned with pool fire about many used kerosene and diesel oil. In order to know the thermal effects of kerosene and diesel oil, temperature change in the pool fire of these fuels were obtained as a variation of combustion time and the tank's height and diameter by using the data acquisition system, And fuel combustion velocity were derived as a function of the diameter and wall thickness of tanks and combustion time. As a result, when the tank's height was 15㎝, the greater diameter the higher temperature rising regardless of tank's wall thickness and fuels. But, when the tank's height is 30㎝, temperature rising was not higher than 15㎝. Also, temperature rising in the pool fire of kerosene much higher than diesel oil. Kerosene's combustion velocity was about two times faster than diesel oil. And, kerosene's combustion velocity was increased according to the increasing of tank's diameter and combustion time. But, diesel oil's combustion velocity was a little increased or not. Surrounding temperature change of tank with the pool fire was obtained temperature distribution of 0∼35℃ according to the change of tank's diameter and distance from the tank's wall.